Trump faces British backlash over Twitter comments on 'ongoing investigation'

President Donald Trump sounded off via Twitter on Friday morning after several people were injured in a reported London train terrorist incident, and is now facing British backlash over his rapid response.

A reported 18 people were rushed to the hospital on Friday after train passengers fled a car at Parsons Green underground station in West London. There was reportedly a blast on the car, and police have said they are treating it as a terrorist incident.

Trump potentially revealed a detail about the culprits involved in one of his morning tweets, saying the perpetrators were "in the sights of Scotland Yard."

"Another attack in London by a loser terrorist.These are sick and demented people who were in the sights of Scotland Yard. Must be proactive!" President Trump tweeted.

UK Prime Minister Theresa May was asked Friday about the U.S. president's tweet on the incident, to which she responded critically that it is "never helpful for anyone to speculate on what is an ongoing investigation."

Click through to read Trump's tweets about the London underground attack:

The information Trump tweeted, if true, comes from the U.S. president before it has been announced by British officials -- a situation similar to when classified information was leaked in the U.S. press about the Manchester bombings.

Former chief off staff to May, Nick Timothy, also weighed in on the U.S. commander in chief's tweet, saying it was "unhelpful."

"True or not - and I'm sure he doesn't know - this is so unhelpful from leader of our ally and intelligence partner," Timothy tweeted.

Trump also used the Friday attack on London's underground to call for a "larger, tougher" travel ban.

"The travel ban into the United States should be far larger, tougher and more specific-but stupidly, that would not be politically correct!" Trump said.

The U.S. Supreme Court earlier this week ruled 5-4 in favor of lifting restrictions on Trump's ordered travel ban until further notice.